Effects of an early handling-like procedure and individual housing on anxiety-like behavior in adult C57BL/6J and DBA/2J mice

Abstract

Manipulations of rearing conditions have been used to examine the effects of early experience on adult behavior with varying results. Evidence suggests that postnatal days (PND) 15-21 are a time of particular susceptibility to environmental influences on anxiety-like behavior in mice. To examine this, we subjected C57BL/6J and DBA/2J mice to an early handling-like procedure. Pups were separated from dams from PND 12-20 for 30 minutes daily or received standard care. On PND 21, pups were weaned and either individually- or group-housed. On PND 60, anxiety-like behavior was examined on the elevated zero-maze. Although individually-housed animals took longer to enter an open quadrant of the maze, they spent more time in the open than group-housed animals. Additionally, we observed a trend of reduced anxiety-like behavior in C57BL/6J, but not DBA/2J mice that underwent the handling-like procedure.

Figure 1. Percentage of Time in Open Quadrants of Elevated Zero-Maze.

Data are presented as means ± SEM. A. Sex x strain interaction. Groups that do not share a common lowercase letter are significantly different at the level, p<.05. B. Main effect of housing, p<.05. C. Interaction of Strain x Handling. The effect did not quite reach statistical significance, p = .065. B6  =  C57BL/6J, D2  =  DBA/2J, Group  =  Group Housed, Individual  =  Individually Housed, No EHLP  =  undisturbed other than routine animal care, EHLP  =  Early Handling Like Procedure.